The present invention relates to an image forming apparatus and an image forming method having a function of storing an original image read out through an automatic document feeding device or an original document table, into a page memory, and of change the order of images stored in the page memory.
In an image forming apparatus which converts an image of an original document set on an original document table into electric signals and prints the image on a paper sheet, it is possible to change the order of original documents read and the order of images to be outputted (by means of electronic sorting) if the image forming apparatus has a page memory capable of storing a plurality of images of original documents. A plurality of sets of paper sheets outputted after electronic sort are stapled and fed out, one after another, onto a tray. Also, this image forming apparatus applies an ADF input method in which layered original documents are subjected to one copy instruction with use of an automatic document feeding apparatus (ADF) and a manual setting input method in which original documents are set on a glass surface (of an original document table) and are subjected to copying, one after another, by manually pressing a copy button.
In case of the ADF input method, layered original documents are always fed from the lowest one and fed to the original document table, so that the order of documents to be read is constant. In case of the manual setting input method, original documents can be set either in an order from the top page or from the last page.
In a conventional image forming apparatus, since the manual setting input method adopts the same processing as in the ADF input method, original documents are read in the order from the lowest original document layered, i.e., from the last page. Therefore, if inputting is started manually from the top page, printing is also carried out from the top page so that the top page is fed out to the lowest layer, thus resulting in miscopy. When miscopy occurs, original documents must be inputted again from the first.
As has been explained above, since a conventional image forming apparatus adopts the same processing as the ADF input method, original documents can be read only in the order from the lowest one of the placed original documents, i.e., from the last page. Therefore, if a user once started inputting original documents from the first page, printing is started from the first page and the first page is fed out at the lowest position, thus resulting in a problem of miscopy. In this case, original documents must be inputted again from the first.